Improvements in information stores

1,005,542. Permanent data stores. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 28, 1963 [March 28, 1962], No. 11824/62. Heading G4A. A read-only store comprises drive conductors 6, 7 formed into S-shaped loops, and sense conductors 4, the limbs of each S overlying a sense conductor. If current is passed through a drive conductor, the induction on a sense conductor due to the upper loop of the 8 balances that due to the lower loop. Data storage is effected by punching holes 9 in a copper sheet positioned so that the holes overlie the lower loops. Where a hole is present, the induction in the sense conductor due to the lower loop is greater than that due to the upper loop and an E.M.F. is generated in the sense conductor. Ternary information may be stored by selectively positioning the holes over the upper or lower loops. In a second embodiment, to reduce capacitive coupling between sense and drive conductors, the drive conductors are shaped as in Fig. 4 and the holes are positioned over the loops EFGH, WXYZ. Shielding conductors 5 are provided to prevent interference between storage locations. The roles of the sense and drive conductors may be reversed.